The present invention relates to ink jet recording apparatuses and particularly to ink jet recording apparatuses using ultraviolet ray hardening type inks.
Conventionally, compared to the gravure printing method and the flexo-graphic printing method, ink jet recording apparatuses have come to be used widely because it is possible to reduce the cost when carrying out small-lot printing jobs since no plate making process is necessary, because it is possible to print on various types and sizes of recording media, and because images equal in quality to silver halide photographs, and other reasons.
In recent years, in such ink jet recording apparatuses, ultraviolet ray hardening type inks such as radical polymerization type inks or cation polymerization type inks are being used because it is possible to print on various types of printing media using such ink jet apparatuses, and several recording heads of each color have come to be arranged in ink jet recording apparatuses in order to carry out high quality and high speed printing on still wider range of types of recording media.
However, when recording is done using plural recording heads, there is the problem that ink clogging occurs in the nozzles of the recording heads due to ink remaining in the recording head or due to paper dust or paper waste accumulated near the nozzles, thereby causing degradation of the image quality due to ink dot dropouts.
In view of this, as is indicated in Patent Document 1, there have been proposals to provide maintenance apparatuses in ink jet recording apparatuses to carry out maintenance of the recording heads. In the maintenance head of such a maintenance apparatus, the cap bases (which are coupling sections) for carrying out the maintenance tasks of suctioning the ink in the recording heads of each color are arranged to correspond to the recording heads of different colors that are arranged in a zigzag manner while being adjacent to each other. Thus, deterioration in the recorded image quality is attempted to be prevented by preventing nozzle clogging by carrying out maintenance of all the plural recording heads using this maintenance apparatus.
Patent Document 1: Japanese Patent Application Laid Open No. 2003-127407
However, as is indicated in Patent Document 1, there is the problem that arranging the same number of maintenance units in the maintenance apparatus as the number of recording heads not only increases the manufacturing cost but also makes the maintenance apparatus very large in an ink jet recording apparatus requiring a large number of recording heads.
Further, in the conventional maintenance apparatuses, since no cover for preventing exposure to ultraviolet rays from the ultraviolet ray irradiating apparatus had been provided and since light shut off measures were insufficient, the ink remaining in or the ink adhering to the cap bases become hardened due to the ultraviolet ray irradiation during the operation of the ink jet recording apparatus or due to the ultraviolet rays in the ambient natural light, particularly in the case of ultraviolet ray hardening cation type inks that are more susceptible to accumulate optical activation energies. Because of this, there was the problem that it is not possible to carry out thoroughly the maintenance operations such as suction using cap bases etc., thereby leading to defects of the ink jet recording apparatus.